How was Oliver's birth itself a victory over circumstances?

The circumstances in which Oliver Twist came into the world were extremely difficult for him and his mother both. He was born in a workhouse, and, at the time of his birth, the surgeon was unsure whether he would "survive to bear any name at all." When he was born, Oliver found it difficult to breathe, and there was nobody to help out except an old woman who had consumed "an unwonted allowance of beer," and a parish surgeon who was obligated to serve the workhouse, but evidently did not particularly want to. Oliver had to therefore struggle alone to breathe, and it was a surprise when he began crying.
Oliver's mother, upon hearing her child cry, asked to see it "and die," being sure that she was nearing the end of her life. Shortly after being given her child, she did indeed die, and the surgeon noted that she had worn no wedding ring.
So, having been born in a workhouse, not breathing, to a woman who was not married, in the presence of one parish surgeon and one drunken old lady, the mere fact that Oliver was able to survive this experience was rather a victory over his circumstances. He could, very likely, have died at birth.